The subject matter disclosed herein relates to heat exchangers and their operation, and more particularly to heat exchangers that are subject to condensate formation on heat transfer surfaces.
Heat exchangers are widely used in various applications, including but not limited to heating and cooling systems including fan coil units, heating and cooling in various industrial and chemical processes, heat recovery systems, and the like, to name a few. Many heat exchangers for transferring heat from one fluid to another fluid utilize one or more tubes through which one fluid flows while a second fluid flows around the tubes. Heat from one of the fluids is transferred to the other fluid by conduction through the tube walls. Many configurations also utilize fins in thermally conductive contact with the outside of the tube(s) to provide increased surface area across which heat can be transferred between the fluids, improve heat transfer characteristics of the second fluid flowing through the heat exchanger, and enhance structural rigidity of the heat exchanger.
One of the primary functions of a heat exchanger is to transfer heat from one fluid to another in an efficient manner. Higher levels of heat transfer efficiency allow for reductions in heat exchanger size, which can provide for reduced material and manufacturing cost, as well as providing enhancements to efficiency and design of systems that utilize heat exchangers such as refrigeration systems. However, there are a number of impediments to improving heat exchanger system efficiency. One such impediment is the formation of condensate on heat transfer surfaces. When condensate forms, it can adversely impact the efficiency heat transfer between a flowing gas and the heat transfer surfaces on which the condensate has formed. In some applications such as refrigeration, the condensate can freeze, which can further adversely impact efficiency. In salty environments such as maritime environments, the presence of condensate can also provide liquid water to form an electrolyte that can lead to galvanic corrosion of heat exchanger components